Caption: Nasal passages and frontal sinuses. Coloured computed tomography (CT) scan of a coronal section through the face of a 65 year old woman showing her nostrils and frontal sinuses. The nostrils (nasal passages, orange, centre) allow air into the nose where it passes to the lungs. The frontal sinuses (upper centre, orange) are part of the network of sinuses (air spaces) around the nose and eyes which lighten the skull and improve the resonance of the voice. The flesh of the cheeks is seen at lower left and right (yellow/green), while the orbits of the eyes are at centre left and right (black). Some of the structure of the eyes can be seen in the orbits (blue/red/green).